Document Detail

Plasma potassium changes with high intensity exercise.
MedLine Citation:
PMID:  2348388     Owner:  NLM     Status:  MEDLINE    
1. Exercise seems to change the extracellular potassium concentration far beyond the narrow limits seen in resting subjects. To examine alterations in plasma potassium concentration during exercise, twenty healthy, well-trained men ran on the treadmill at 6 deg inclination with catheters inserted in the femoral vein and artery. 2. During 1 min exhausting exercise plasma potassium concentration rose in parallel in the vein and artery, reaching peak post-exercise values of 8.34 +/- 0.23 mmol l-1 and 8.17 +/- 0.29 mmol l-1. After 3 min recovery the potassium concentration was 0.50 +/- 0.05 mmol l-1 below pre-exercise values. Both the rise of plasma potassium concentration during exercise and the decline during recovery followed exponential time courses with a half-time of 25 s. 3. Exercise at reduced intensity showed that the peak post-exercise potassium concentration was linearly related to the exercise intensity. Individual resting, peak and nadir values were proportionally related. 4. The increased potassium concentration during exercise can be explained in full by the electrical activity in the exercising muscles. Repeated 1 min exhausting exercise bouts revealed no relationship between potassium concentration and plasma pH nor glycogen break-down. 5. All of the observations fit a simple model of potassium efflux from active muscle and elimination from blood with the following characteristics: the efflux increases (decreases) stepwise at the onset (end) of exercise, and the efflux rate during exercise increases with exercise intensity. Potassium is eliminated from blood by a proportional regulator which may be the Na(+)-K+ pump of the exercising muscle. Extracellular potassium is indirectly linked to the pump stimulus, and the rate of reuptake is proportional to the extracellular accumulation. Thus no limited maximal power for potassium uptake was found. The post-exercise undershoot of 0.5 mmol l-1 can be explained by a higher gain of the pump after exercise. 6. The large, rapid changes in the plasma potassium concentration during and after exercise is due to the first order kinetics of the reuptake mechanism rather than to a limited power to take up potassium.
J I Medbø; O M Sejersted
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  421     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1990 Feb 
Date Detail:
Created Date:  1990-07-12     Completed Date:  1990-07-12     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  105-22     Citation Subset:  IM    
Department of Physiology, National Institute of Occupational Health, Oslo, Norway.
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MeSH Terms
Exercise / physiology*
Femoral Artery / physiology
Femoral Vein / physiology
Hydrogen-Ion Concentration
Physical Endurance / physiology
Potassium / blood*
Time Factors
Reg. No./Substance:

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